It takes about 3 feet of head to get 1 psi, so I would guess that the correct reading, if the pressure sensor is at carburetor level would close to 1 psi. But if you are reading a steam gauge in the panel, or a pressure sensor mounted above the carburetor level, it depends on whether the pressure sense line is full of fuel or air. It will probably be full of fuel if it has been installed for some time, but if you just installed it there will be air in it. So it's not exactly simple if you are trying to get an exact reading.
Gary Csey
From Bill:
Assuming that you have a header tank, you should show 1 or 2 psi fuel =
pressure at the carb with everything shut down. It=E2=80=99s simply =
gravity head pressure. Yet another advantage of header tanks. Did you =
also check the oil pressure with a steam gauge?=20
Bill Harrelson
N6ZQ IV 500 hrs.